To provide a corner sealing and blocking member with a simple structure and proper working efficiency.

A corner step 11 is installed in a corner region of a vertical passage opening of a building scaffold. An engaging hook 21 engaging with a vertical member for engaging is mounted on a first side 13 of the body plate 12, and a small projection piece 26 is provided in a position separated from the engaging hook 21 on the first side 13. The engaging hook 21 is constituted of a first hook piece 22A and a second hook piece 22B having an U-shaped appearance as a whole, and both of the hook pieces 22A, 22B are separately arranged at an interval equivalent to a width of a horizontal member. A first bent part 24a and a second bent part 24b formed at vertical positions of both of the hook pieces 22A, 22B point in mutually opposite directions. By using the engaging hook 21 having such a constitution, the engaging hook 21 can be engaged with the horizontal member 32a and the vertical member 38 so as to improve workability.